I am seeing this as well. 4x5-minute samples of data, then 2x5-minutes of missing data. I have an SR open w/ VMware to investigate. I did not have this issue prior to upgrading to 5.1. My backend database is Oracle.
Are you using Oracle or MS SQL? Also, are you only seeing gaps in the daily view, or is it in weekly and montly as well? I've got a case open with Vmware, so far I haven't made any progress.
Thanks,
Clint